i'm having a hard time identifying a set of vintage flat bars that i own.
not too sure if "stemless" is the proper nomenclature, but my friends, local shop, and myself are completely stumped.
any help at all would be greatly appreciated.

Those are called Bullmoose bars and designed by Tom Ritchey. Very popular in the EARLY days of mountain biking. More info and replacement (sometimes, expensively) available here:

https://www.rivbike.com/products/list...product=16-198

I had a bike or two with those. Like all early MTB-specific parts, they weighed a ton but were quite literally bomb-proof. Well, depends on the bomb - they probably wouldn't survive a large h-bomb but would probably stand up to a small tactical nuke.....

Standard mountain bike bars from the early to mid 1980s. Nick name for them was bulls horn bars. My 1984 Trek 850 had them for example. Roger

Why would you need help ? The bar's strange for sure. It appears to simply be a bar set-up with an unconventionally attached stem, I've seen'em.
If you wanted to replace them or just to know, it's a 1 1/8 "threadless steerer" design. The most common type/size used on Mountain Bikes for many years. You would buy a "threadless" stem and a bar, 1" flat or hi-rise or...
The bars look OK though. To buy different is cheap for such bikes. www.jensonusa.com
Just to look, using my given specs.

thanks guys.

You mean, "threaded" not "threadless", right? Those things pre-date threadless by close to a decade, I would think. I would also guess they predate 1 1/8" too but not for sure. I would guess 1" but I suppose 1 1/8" would be possible. Easy to measure or the dude at the bike shop can probably tell by looking. Hard to tell from pictures......

The link says it's QUILL, which could be either 1" or 1 1/8" THREADED
It appears to be threadless, if you make sure of that in either case you're OK.
Quills extract stem an' all, using an exp. wedge screwed to the long center bolt.
Threadless has a stem grasping the the steerer. The on-line cat. I'd listed shows..

Guys at the shop can tell, why they didn't already is questionable.

All correct, except threaded, not threadless, and (probably) 1", not 1 1/8".

+1 with GV27. Correct generic term is bull moose bars. Bull horn is the generic name for the upturned bars used on time trial bicycles. It's not a threadless steerer design as suggested.

My link? Yeah, the Riv ones are 1" quill. The OPs are DEFINITELY threaded (aka quill), NOT threadless (aka Ahead-Set). Check out the lock nuts in his pics.

I can see how it would be easy to make that mistake. The stem looks very much like a Threaded-to-Threadless Stem adapter with a set of bars welded to it.

Well yeah, I suppose that's basically what it is!

Nitto/Ritchie bullmoose bars show up on eBay once in a while. Mine are black anodized aluminum and I paid $25 for them. I understand they are worth more. They had never been mounted when I bought them, but they have now. Most of the bullmoose bars that I've seen have been chromed steel.